Quiz on Raft

Test your understanding of the Raft consensus algorithm.

Question 10

If we use the Raft algorithm for a geo-replicated storage system similar to S3, what would be a reasonable number of Raft nodes?

Hide Answer

S3-like systems enable their users to configure the required replication factor and select the geographical places where replication should happen. Typically 3 or 5 replicas are common, while critical data might require 7 replicas. So there will be as many nodes in the Raft cluster as the number of data replicas.

There are many interesting, open questions in this scenario, for example:

  • Should there be different Raft instances per S3 bucket, per S3 client, or just one for the data center involved?

  • How should the timer for values of election and other operations be adjusted, especially when one Raft node might be far away from the other, which can result in substantial propagation delays?

We leave the answers to these questions for you to ponder upon.

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Log Compaction and Client Interaction in Raft

Conclusion